In carrying out an evaluation test of signal transmission property or the like of an IC device such as a BGA (ball grid array) device, an IC socket, having contacts each connectable to each terminal of the IC device, is used. In recent years, a frequency of a signal used in the IC device becomes higher, as a processing speed of the IC device becomes higher. Corresponding to such a high-speed signal, the IC socket is required to transmit the high-speed signal.
In order to transmit the high-speed signal, it is preferable that a self-inductance of a contact pin included in the IC socket is low. Therefore, in general, it is preferable that the contact pin has a short length and a large diameter.
Another method corresponding to the high-speed signal is described in Patent Literature 1. Patent Literature 1 describes that “an LSI socket 101 of the invention is constituted by a printed board 102, a POGO pin 103 and a POGO pin supporting case 104. Printed board 102 has a plurality of through holes 109, into which POGO pins 103 are inserted. POGO pins 103 include a first power source pin 105, a second power source pin 106 having an applied voltage different from the first power pin, a GND pin 107 and a signal pin 108. On an inner surface of each through hole 109 other than through hole for signal pin 108, a plated layer 116 is formed.”
Patent Literature 2 describes that “in general, a bypass chip capacitor for a power supply probe is mounted on a wiring pattern, which is electrically close to a device as possible, in a printed board at a lower side of a testing socket” and “it is necessary to mount the chip capacitor on an upper part of the testing socket, where is directly below a device to be tested.”